function countTime() {
       	//获取当前时间
       	var date = new Date();
       	var now = date.getTime();
       	//设置截止时间
       	var endDate = new Date("");
       	var end = endDate.getTime();
       	//时间差
       	var leftTime = end - now;
       	//定义变量 d,h,m,s保存倒计时的时间
       	var d, h, m, s;
       	if (leftTime >= 0) {
       		d = Math.floor(leftTime / 1000 / 60 / 60 / 24);
       		h = Math.floor(leftTime / 1000 / 60 / 60 % 24);
       		m = Math.floor(leftTime / 1000 / 60 % 60);
       		s = Math.floor(leftTime / 1000 % 60);
       	}
       	//将倒计时赋值到div中
       	document.getElementById("_d").innerHTML = d + "天";
       	document.getElementById("_h").innerHTML = h + "时";
       	document.getElementById("_m").innerHTML = m + "分";
       	document.getElementById("_s").innerHTML = s + "秒";
       	//递归每秒调用countTime方法，显示动态时间效果
       	setTimeout(countTime, 1000);
       }